JPH06112122A - Two-dimensional quantum device structure - Google Patents

Abstract

PURPOSE:To remove crystal defect, and to form a small-gage wire in size and a shape, in which a sufficient quantum confinement effect is generated, by forming a diffraction grating onto a semiconductor substrate having a {111} face and growing a semiconductor crystal on the diffraction grating through an MBE method. CONSTITUTION:A diffraction grating 52 with pitches A1 is formed on the surface of a semiconductor substrate 51 having a face azimuth inclined within a range of 0.5-15 deg. with respect to a {111} face in the semiconductor substrate 51, and a semiconductor crystal is grown on the diffraction grating 52 through one method of an MBE method, a GSMBE method, an MOMBE method and a CBE method. Conditions, in which a growth rate on the {111} face slowed, are selected as the conditions of growth at that time. Accordingly, a saw-tooth- wave shape 53 consisting of a terrace surface made up of the {111} face and a stepped section composed of a {100} face can be shaped, and periodic structure having a period of 1/N to periodic structure formed on the inclined substrate can be introduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a structure of a semiconductor device including a two-dimensional quantum well structure on a diffraction grating in order to realize a semiconductor laser having a low threshold current density, a transistor operating at a high speed, and the like. The present invention relates to formation of a diffraction grating conforming to the above, and further relates to a method of manufacturing a semiconductor crystal on the diffraction grating. The present invention is applied to the production of semiconductor devices having high-performance electronic characteristics and optical characteristics.

[0002]

2. Description of the Related Art Research has been conducted on a semiconductor structure in which a diffraction grating is formed on a semiconductor substrate and a layer having a second periodic structure deviated from the phase of the periodic structure of the substrate is grown thereon.

Diffraction gratings are used in various optical circuit devices such as filters, optical couplers, distributed feedback (DFB) lasers and distributed Bragg reflection (DBR) lasers in the field of optoelectronics. In particular, a diffraction grating formed for a wavelength control or wavelength tunable semiconductor laser represented by a DFB or DBR laser is used as a resonator of a laser. In addition, the period, shape, and depth of the diffraction grating are important factors that determine the laser characteristics (oscillation threshold, coupling coefficient, etc.), and it is necessary to create a highly accurate diffraction grating in such a laser with good controllability. Has become an important issue in this technical field.

Conventionally, the diffraction grating is formed by a two-step method of forming a grating photoresist mask and etching. However, since the period of the diffraction grating in the field of optoelectronics is as small as 0.1 to 1.0 μm, the conventional photolithography technique cannot be applied to the production of the photoresist mask. Therefore, the holographic exposure method has been generally used. This is an exposure method using the interference of laser light, and its process will be schematically described with reference to FIG.

As shown in FIG. 1 (a), a substrate 1-21 is coated with a photoresist 1-22, and two sufficiently parallel laser beams 1-23, 1-24 are applied in two directions ( In the illustrated example, irradiation is performed from two directions forming an angle of θ with respect to the perpendicular, and interference fringes are formed to periodically expose the photoresist, and this is developed and baked to form a lattice as shown in FIG. A photoresist mask 1-25 in the shape of a circle. Next, using the photoresist mask as an etching mask, etching (wet or dry etching) is performed as shown in FIG. 3C, and then the etching mask is peeled off to form a periodic structure (diffraction grating) on the substrate as shown in FIG. ) Transferring 1-26.

In the holographic interference exposure method, assuming that the incident angle of two laser beams is θ and the wavelength of the laser beams is λ, the lattice spacing Λ (see the figure (b)) that can be produced is Λ = λ / (2sinθ). ). As an exposure laser, an Ar laser (λ = 351 nm) or H
An e-Cd laser (λ = 352 nm) is suitable. Λ ≦
To make a mask of about 0.25 μm, a He-Cd laser is used.
Use the Z. On the other hand, the oscillation wavelength λ of the DFB and DBR semiconductor lasers has the following formula λ = λ ₀ / N _eff = 2Λ / m (m = 1,
2. ． ． ) Can be represented. Where λ ₀ / N _eff is the Bragg wavelength in the medium, N _eff is the equivalent refractive index of the medium,
λ is the period of the diffraction grating in this semiconductor laser. The case of an integer m = 1 means the first-order diffraction, and the case of m = 2 means the second-order diffraction.

In such a semiconductor laser, for example, G
In the case of a short wavelength using aAs as the active layer, the period Λ of the diffraction grating is expressed by the above formula (1) when the oscillation wavelength is 0.8 μm.
It is assumed that the next diffraction is used) to about 115 nm. Even when the m-th order diffraction is used, 11
It is only about m times 5 nm larger. Therefore, in order to reduce the wavelength of the exposure laser beam when creating the diffraction grating, even if the wavelength λ = 325 nm of the He-Cd laser is used, the grating for the first-order diffraction is set in the air. It cannot be created.

Therefore, GaAs short wavelength DFB, DBR
The following three methods can be given as methods for forming the first-order diffraction grating (period Λ = 130 nm or less) of the semiconductor laser.

As a first method, there is a method of immersing a sample in a high refractive index medium and performing interference exposure in the medium to shorten the period of the diffraction grating by the refractive index of the medium. As the high refractive index medium, for example, xylene, which absorbs little light, is used. Further, as a similar method example, there is a method in which a triangular or rectangular prism is placed on the photoresist film via a refractive index matching oil, and two light beams for exposure are made incident from both sides of this prism.

The second method is to halve the period of the diffraction grating obtained by the two-beam interference exposure method by further processing. As shown schematically in FIG. 2A, first, a plurality of grooves (diffraction grating) 2-27a are formed on the substrate 2-27.
And then an etching mask material (photoresist) 2-28 is formed on the entire surface. After this, as shown in FIG. 2B, the etching surface is exposed by exposure and development, and then etching is performed as shown in FIG. 2C, and thus, as shown in FIG. A half diffraction grating of -27a is obtained.

As a third method, as schematically shown in FIG. 3, a photoresist mask 3-29 is first formed on a substrate 3-30 by a two-beam interference exposure method as shown in FIG. , And then ECR-CVD on it as shown in FIG.
The SiNx film is grown by the method described above, and the etching time is adjusted as shown in FIG.
Etching masks 3-29, 3-32 by x are formed, etching is performed using this mask, and as shown in FIG. 3D, a diffraction grating 3-33 that is half of the photoresist mask with the first period is formed. There is a way to create.

Fabricating a wafer laminated structure on the fabricated diffraction grating is a very important technique for improving the semiconductor technology and the threshold current density of a laser. A semiconductor device using a superlattice structure has attracted attention because it enables a semiconductor laser with a lower threshold current and a transistor operating at higher speed than conventional ones. One of the superlattice structures currently under study is a one-dimensional quantum well. The structure (quantum thin film) is the mainstream, and a semiconductor laser using this is described in the following documents.

Tsaug, TW: "Extremely Low Threshol
d (AlGa) As Modified Multi-Quantum Well Heterostru
ct Lasers Grown by Molecular Beam Epitaxy "Appl. Ph
ys. Lett., 39, p786-788 (1981) Compared to the one-dimensional quantum well structure, the two-dimensional quantum well structure (quantum wire) and the three-dimensional quantum well structure (quantum box) become higher dimensional. It is expected that it will be possible to manufacture a device having the above characteristics.

FIGS. 4 (a), 4 (b) and 4 (c) are conceptual views of the one-dimensional, two-dimensional and three-dimensional quantum well structures, respectively, and FIGS. 5 (a) and 5 (b). 4C is a diagram showing the relationship between the density of states of electrons and the energy shown in FIGS. 4A, 4B, and 4C.

The density of states of the one-dimensional, two-dimensional and three-dimensional structures in the bulk crystal state is parabolic as shown by the broken line in FIG.
In the dimensional quantum well structure, the density of states changes in a staircase shape, a sawtooth shape, and a pulse train shape, respectively. Since it is expected that the light absorption and the light emission state will also change sequentially with such a change in the state density, a semiconductor laser having an extremely low threshold value is expected. Further, in the two-dimensional quantum well structure, it is expected that the electron mobility will be increased by simplifying the scattering mechanism, which is important from the aspect of electronic devices.

The quantum wire laser using the two-dimensional quantum well structure and the quantum box laser using the three-dimensional quantum well structure are expected to have the following effects due to the above features. (1) Low threshold laser. (2) The temperature dependence of the threshold current is small. (3) Improvement of high-speed modulation by increasing relaxation oscillation resonance frequency. (4) The line width of the oscillation spectrum is narrowed.

As described above, increasing the dimension of quantization has various advantages, but its manufacturing method is still in the development stage. As a manufacturing method currently being studied, the method shown in FIGS. 6A to 6D described in JP-A-63-94615 is mainly used. Here, the principle of the manufacturing method will be described extremely schematically with reference to FIGS. 6 and 7.

In FIG. 6A, the substrate having the (100) plane as its surface is tilted in the (011) direction by several degrees. Such an inclined surface can be considered as a combination of the (100) surface and the (011) surface, where 131 is the (100) surface and 133 is the (011) surface. Now, it is assumed that the AlAs molecules 132 fly onto the crystal surface (100) of 131. Then this A
Since the 1As molecule 132 is unstable on the (100) surface, it re-evaporates or migrates on the (100) surface. However, when the molecule comes to the step where the (011) plane of 133 exists, the AlAs molecule 132 is adsorbed at this step to form a crystal plane. As shown in FIG. 7B, the AlAs molecules 132 are sequentially absorbed in this step and become crystals. Change the molecule supplied here. First, as shown in FIG. 6C, the supply of AlAs molecules 132 is stopped, and an AlAs layer is formed up to half of the (100) plane.
Next, when the supply molecules are changed to the GaAs molecules 134 and supplied, growth is performed according to the same principle, and GaAs and AlAs regions are formed in the lateral direction as shown in FIG. The film thickness 135 of each layer is formed in units of one atomic layer.
By repeating the growth shown in FIGS. 7C and 7D, it is possible to form a crystal structure in which the GaAs layer 141 and the AlAs layer 142 extend in the vertical direction as shown in FIG. A quantum wire can be produced by using a substrate tilted in this way and changing the supplied molecular species.

On the other hand, the method of crystal growth will be described in detail below.

Quantum wires in which electrons and holes, which are carriers in a semiconductor, are confined in a one-dimensional narrow space and two-dimensional superlattices in which the quantum wires are periodically arranged are new electrons different from bulk semiconductor crystals. It is predicted that physical properties and optical properties will appear. For example, when quantum wires are used for the active layer of a semiconductor laser, the threshold current for laser oscillation can be lowered, and moreover, a sharp emission spectrum can be stably obtained against temperature changes. In addition, since the mobility of electrons in quantum wires reaches about 10 ⁷ to 10 ⁸ cm / V · sec, a field-effect transistor (FET) having a high-speed property similar to a high-speed mobility transistor (HEMT) or a unique function. It is expected to be applied to devices.

For these reasons, attempts to produce quantum wires and two-dimensional superlattices have become popular in recent years. Regarding quantum confinement in the one-dimensional direction, currently MBE
It is possible to manufacture with high precision by the thin film forming technology including the method. On the other hand, in order to fabricate a quantum wire that confine carriers in a two-dimensional direction, the energy band is modulated not only in the film thickness direction but also in the in-plane direction, and the region corresponding to the band well is confined in the barrier region. Some means is needed. The methods proposed and studied so far as methods for producing quantum wires and two-dimensional superlattices are classified into the following three types.

(Prior Art Example 1) A method of directly utilizing a fine processing technique such as lithography or etching as a means for forming an interface for confining a GaAs well region in an in-plane direction.

(Prior art example 2) A GaAs well layer and an AlGaAs barrier layer are formed on a (001) OFF substrate of GaAs on which irregularities are formed in advance, by using a metalorganic vapor phase epitaxy (M
OVPE) method is used for the growth. At that time, a quantum wire is formed at the bottom of the V-groove or a step portion of a saw blade shape by utilizing the difference in growth rate depending on the crystal orientation.

(Prior Art Example 3) If growth conditions are selected in the case of MBE growth on a GaAs substrate having a surface orientation slightly tilted from the (001) plane, crystal growth proceeds by movement of atomic steps. To use. At that time, in a time shorter than the time interval for forming one atomic layer, G
A method of forming a quantum wire structure by alternately growing aAs and AlGaAs.

[0025]

SUMMARY OF THE INVENTION 1 for the short wavelength (λ = 0.8 μm) DFB and DBR semiconductor lasers described above.
The following problems have been encountered in the method of forming the next-order diffraction grating (period Λ = 130 nm or less).

In the first method, the light wavefront of the exposure beam is disturbed due to scattering and multiple reflections caused by the liquid and its container, and is easily affected by the vibration of the apparatus and the fluctuation of air, and the diffraction grating However, there is a problem that the accuracy of is deteriorated.

In the second method, the exposure / development conditions are strictly controlled after the photoresist film is formed on the entire surface as an etching mask, and variations occur in the surface, which deteriorates the accuracy of the diffraction grating. Further, if wet etching is used in the second etching, there is a problem in that the diffraction grating shape becomes irregular.

In the third method, it is difficult to control the etching conditions for the SiNx film on the resist and the SiNx film on the substrate. Further, during etching, if the etching is dry etching, the etching mask is made of two kinds of materials, that is, a resist and a SiNx film, so that there is a difference in resistance to the etching gas and the diffraction grating shape becomes irregular, and the depth and dimension accuracy deteriorates. There is a problem.

Therefore, in view of the above-mentioned problems, the present invention is based on a new principle and has a short wavelength (λ = 0.8 μm) DF.
It is an object of the present invention to provide a method for producing a diffraction grating capable of forming an extremely fine diffraction grating for first-order diffraction of B, DBR lasers, etc.

The above-described conventional method for manufacturing a two-dimensional quantum well structure utilizes the periodicity of AlAs and GaAs, but each layer of AlAs and GaAs does not necessarily exhibit a constant periodicity, and FIG. 141 and 142, the widths of the GaAs layer and AlAs layer often vary within the growth substrate plane. In this case, there is a problem that the quantum wires of the two-dimensional quantum well structure produced vary, and the quantum level and the density of states are greatly deteriorated.

The present invention provides a method for producing a laser having a two-dimensional quantum wire with good reproducibility without causing the above-mentioned problems. In addition, there are some problems in the above-mentioned conventional example as a method of manufacturing a quantum wire. In Conventional Example 1, it is difficult to escape from the influence of the generation of crystal defects and the inclusion of impurities accompanying the fine processing. Furthermore, it is almost impossible to realize a two-dimensional superlattice in which quantum wires are densely arranged by this method.

It can be said that the prior art example 2 is superior to the prior art example 1 in that the quantum wire structure is formed in one growth process and therefore there is almost no risk of occurrence of crystal defects and inclusion of impurities. However, the problem of Conventional Example 2 is that the confinement of carriers is not sufficiently exhibited because the size and shape of the thin wire that can be manufactured are greatly restricted. Moreover, the region in which the quantum wires can be produced is extremely limited depending on the dimensions of the substrate processing. Therefore, it is difficult to manufacture a two-dimensional superlattice.

The prior art example 3 is a method in which quantum wires can be arranged at a high density in principle, but since this method is essentially susceptible to statistical variations and fluctuations accompanying the surface diffusion process of atoms, Until now, fabrication of a good quality two-dimensional superlattice has not been realized.

The problems of this part which the present invention is trying to solve by overcoming the problems of the conventional example are the following four items.

1. No crystal defects or impurities are mixed in.

2. Being able to form fine wires with a size and shape that will produce a sufficient quantum confinement effect.

3. Reproducibility is good and fine line morphology can be formed without being affected by fluctuations caused by atomic diffusion.

4. Quantum wires can be arranged in high density and the degree of freedom of arrangement is high.

[0039]

The present invention is a semiconductor having a zinc blende type crystal structure, and has a plane orientation inclined from the {111} plane or the {110} plane within a range of 0.5 to 15 degrees. When the epitaxial growth is performed on the first periodic shape surrounded by the planes having different indices in the semiconductor substrate having the second periodical pattern having the new periodicity by utilizing the difference in the growth rate depending on the plane orientation of the growth. It forms a periodic structure.

Here, the {111} plane is the (111) plane, and the (1
Equivalent planes such as the ^* 1 ^* 1 ^* ) plane and the (11 ^* 1 ^* ) plane are included, and the {110} plane is assumed to include the (11 ^* 0) plane and the (110) plane. However, the symbol 1 ^* is especially the number 1 here.
Is used as a substitute for the mirror symbol in which-is written. This description method is applied below.

On a semiconductor substrate having a zinc blende structure represented by GaAs, {111} planes or {110} planes are formed.
By forming periodic irregularities on a semiconductor substrate having a plane orientation tilted in the range of 0.5 to 15 ° from the plane and epitaxially growing on the irregular plane, the growth rate difference due to the plane orientation is utilized to stabilize. To provide a method for producing a quantum wire.

Further, the present invention has a {111} plane or a {11} plane.
The present invention provides a method of forming a diffraction grating on the surface of a semiconductor substrate having a plane orientation inclined in the range of 0.5 to 15 degrees from the 0} plane and growing a semiconductor crystal on the diffraction grating.

More specifically, it comprises the following steps. A schematic description will be given with reference to FIG. The first step is a semiconductor having a zinc blende type crystal structure, {111}
In a semiconductor substrate 51 having a plane orientation inclined in the range of 0.5 to 15 degrees from the plane, a diffraction grating 52 having a pitch Λ ₁ is formed on the substrate surface, and a solid source MBE method or a part of molecules is formed on the diffraction grating 52. A semiconductor crystal is grown by the GSMBE method in which the radiation source is gasified, the MONBE method in which an organic metal is used for the molecular beam source, or the CBE method in which all the molecular beam sources are gasified. The growth condition at this time is to select a condition such that the growth rate on the {111} plane is slow, and the sawtooth shape 53 including the terraced surface formed of the {111} surface and the stepped portion formed of the {100} surface is formed. Can be formed. Further description will be made with reference to FIG. {11
The diffraction grating 55 having the pitch Λ ₁ 1 is formed on the surface of the semiconductor substrate 54 having a plane orientation inclined in the range of 0.5 to 15 degrees from the 0} plane, and the solid source MBE is formed on the diffraction grating 55.
Method, a GSMBE method in which part of the molecular beam source is gasified, a MOMBE method in which an organic metal is used as the molecular beam source, or a CBE method in which all molecular beam sources are gasified to grow a semiconductor crystal. The growth condition is to select a condition that the growth rate on the {110} plane becomes slow,
Sawtooth shape 56 consisting of terraces made of {110} planes and stepped portions made of {113} planes or {114} planes
Can be formed.

The pitch Λ _{2 of the} sawtooth shape is determined only by the pitch Λ _{1 of the} grating formed below it, and Λ ₂ = Λ ₁ is always satisfied.

As a next step, this sawtooth shape 5
If the growth rate on the terrace surface is slow and the growth rate on the step surface is fast on 3,56, that is, if the growth is performed under the same growth conditions as the growth of the surface having the first inclination, the step disappears. Without maintaining the surface shape, or at least maintaining the periodic structure of the surface, the growth mainly in the lateral direction proceeds.

It is also possible to produce the second periodic structure 63 as shown in FIG. 9A by changing the ratio of the growing molecular beam or changing the type.
The molecular beam can be changed by opening / closing a shutter, opening / closing a valve, or the like, which is usually used when manufacturing a quantum well.

The period of the periodic structure is made to be an integral multiple of the pitch of the diffraction grating by appropriately selecting the modulation time within the time shorter than the time required for the step surface to grow over the Λ ₂ distance. You can also

As described above, a second periodic structure having a specific period is formed on a substrate having an inclined region, for example, a second periodic structure having a period of 1 / N with respect to the formed first periodic structure is grown. It can be made at times. A quantum effect can be provided by setting the size 65 of the step portion of the periodic structure thus formed to 30 nm or less. Further, the size of this portion is determined by the pitch of the diffraction grating shown in 11 and the tilt angles of the (111) plane and (110) plane.

If the refractive index of the substrate forming the diffraction grating is the same as that of the first growth layer, the original diffraction grating does not contribute to the modulation of the equivalent refractive index. As shown in FIG. 9B, the equivalent refractive index of this waveguide is characterized in that it has a large component having a low order with respect to the pitch of the original diffraction grating, that is, a component modulated at a short wavelength pitch. It will also happen. Generally, the crystal growth rate of a semiconductor differs depending on its crystal plane. For example, in the present case, the (111) plane has a slower growth rate than the (100) plane, and the (110) plane is slower than the (111) plane. For more information, see Journal of Applied Physi
Please refer to the article of cs Vol.64, 3522 (1988).

This will be described with reference to FIG. As a first step, a semiconductor having a zinc blende structure, {11
A first periodic structure having a plane orientation inclined from a {111} plane by 0.5 to 15 degrees is formed on a semiconductor substrate having a 1} plane orientation. A gentle cycle with a pitch of 10-5 is formed on the surface of the substrate. Here, the cycle 10-5 is 100 μm
Therefore, the periodic structure 10-6 is formed so that a flat portion, for example, a portion such as 10-03 is not produced. In the figure, 10-1 is the {111} plane, and 0.5 to 1 from the {110} plane.
It is a surface inclined by 5 degrees.

After that, a short period structure is formed on the gentle periodic structure 10-6. This will be described with reference to FIG. An interference exposure method is adopted as a manufacturing method. This manufacturing method will be described in Examples. In FIG. 11, 11-7 is a short-period structure with a pitch of 240 nm, which is manufactured by interference exposure. Here, 11-6 has a long-period structure.

As the next step, the MBE method of the solid source on the periodic structure, the GSMBE method in which a part of the molecular beam source is gasified, the MONBE method using an organic metal for the molecular beam source, or all of them is used. Molecular gas source gasified C
A semiconductor crystal is grown by the BE method. FIG. 12 is an enlarged view of the vicinity of 11-6 in FIG. A semiconductor film 12-8 is grown on the short period structure formed on the sloped portion of the long period structure. At that time, the growth conditions are selected such that the growth rate on the plane {111} plane is slower than that of the inclined surface, {114} or {113}, and the terraces composed of {111} planes and {100} It is possible to form a sawtooth shape 12-11 composed of a step portion of the {} plane. In addition, under the same conditions, a semiconductor film made of a material different from 12-8
Grow 12-9. Similarly, a condition is selected such that the growth on the {111} plane becomes slow. As a result, the semiconductor film 12-9 has a structure that concentrates on the step portion. Similarly 12-
A semiconductor film 12-10 different from the semiconductor film 9 is deposited.
The conditions at this time were also selected such that the growth rate of the {111} plane was slow. By repeating this, regions having different compositions can be partially formed. One important point of this patent is to form surfaces with different growth rates.

Alternatively, a {110} plane substrate may similarly be used to form an inclined surface within the range of 0.5 to 15 degrees. The important points are to form a difficult-to-grow face and a fast-growth face, and to easily control the length of one side of the easy-to-form face, and the width of the slow-growth face compared to the fast-growth face. Is long enough to satisfy these,
The semiconductor region can be easily confined even partially. As a growth method, a solid source MBE method, a GSMBE method in which a part of the molecular beam source is gasified, a MOMBE method in which an organic metal is used as the molecular beam source, or a CBE method in which all the molecular beam sources are gasified To grow a semiconductor crystal.

A specific example will be described. Fig. 13 shows Fig. 11 (a).
It is the figure which partially expanded. 13-21 is a diffraction grating manufactured by interference exposure. Pitch Λ ₁ is 240 nm
Is. A film 13-22 is formed on this film by an epitaxial method.
Are stacked, the width (B) of the step (100) plane, 13-22
Is determined by the following formula.

B = Λ ₁ tan θ / sin θ ′ Here, θ is the inclination angle from the {111} plane and the {110} plane, which is one of the above-mentioned values of 0.5 to 15 °. Here, θ ′ is an angle of 54.7 ° formed by the (111) plane and the (100) plane forming the step. When the inclination angle θ of the substrate is about 5 °, the width B of the (100) formed in steps, 13-22, is 26 nm. A crystal is grown on this by epitaxial growth. For example, in the case of growing a GaAs film on GaAs using the MBE method, the difference in growth rate between the (111) plane and the (100) plane is about 3 times, and the (111) plane is faster. 14
In the step, the quantum well as shown in 14-31 is formed as shown in FIG. Here, 14-3 on the (100) plane
As shown in FIG. At this time 14-33
As shown in Fig. 6, it is about 1/3 of that on the (111) plane 6
nm GaAs is stacked. These 14-32, 14-33
FIG. 5 shows the repetition of the above lamination. Lamination can be easily performed by changing the feed material.

Further, the method of crystal growth will be described. First, {1
A diffraction grating is formed on a semiconductor substrate inclined by 0.5 to 15 degrees from the 11} or {110} plane, and a semiconductor crystal is grown thereon by the MBE method or the GSMBE method. The direction of the incident molecular beam at this time is not particularly limited. However, G
The SMBE method is also called a chemical beam epitaxy (CBE) method, a metalorganic molecular beam epitaxy (MOMBE) method, etc., but these all mean the same method.

Generally, there is a minimum growth rate in the orientation of the low index plane of the crystal, but especially the {111} plane (or {11} plane)
Since the growth rate of the (0} plane) is very slow, a {111} plane (or {110} plane) terrace and a {111} plane (or {110} plane) are formed on the surface along with the above growth. A saw blade shape is formed that is formed by steps having different plane orientations.

At this time, the height S of the step measured in the direction perpendicular to the terrace surface and the cycle T of the saw blade measured in the direction horizontal to the terrace surface use the cycle P of the grating and the inclination angle a of the substrate. And S = P · sin (a) and T = P · cos (a), respectively.

Next, by inclining the direction of at least one kind of molecular beam in the range of 10 to 80 degrees from the normal direction of the substrate, a region where the incident molecular beam is shaded from the step portion to the middle of the terrace surface. Is formed. For this reason, the phenomenon that a new crystal plane grows from the stepped recess and is flattened is suppressed. On the other hand, the growth rate of the terrace surface is extremely slow, and therefore almost no molecules are taken in.Therefore, the molecules incident on the surface reach the step due to surface diffusion and are taken into the crystal,
Alternatively, most of them are released into the vacuum phase, and the ratio of crystallization on the terrace surface is extremely small. As a result, the step does not disappear and the sawtooth shape is retained on the surface, and the lateral growth proceeds almost constantly.

Now, assuming that the lateral growth rate of the step portion is horizontally measured on the terrace surface as Vs and the growth rate of the terrace portion in the direction perpendicular to the terrace surface is Vt, the sawtooth edge shape of the surface is from the substrate horizontal direction. It will translate in the direction of angle b. Here, b is represented as b = a + tan ⁻¹ (Vt / Vs). Since the relationship of Vt << Vs is established between Vt and Vs, the angle b is a value close to the angle a, and the growth progresses substantially in the lateral direction. In the process in which the semiconductor crystal corresponding to the barrier constantly grows laterally as described above, the semiconductor crystal corresponding to the well is grown for t hours,
After that, when the barrier semiconductor crystal is grown again, the cross section of the semiconductor crystal in the well has a structure in which rectangular regions having a width L = Vs · t and a height S are connected with a very thin width d = Vt · t. Become. From the above formula expressing S, the height S of this rectangle is selected by the period P of the diffraction grating and the substrate orientation a, and the width L can be accurately controlled by the time t. As a result, a quantum wire having a fine dimension can be manufactured with high accuracy. Also,
A two-dimensional superlattice in which quantum wires are densely arranged can be formed by repeating the above growth process at an appropriate cycle. Here, the appropriate period is represented by T / (N + 1/2), where N is an integer.

In the above-mentioned conventional example 2 using the MOVPE method, since a new crystal plane is generated from the recess of the step once formed, the step disappears with the growth, and as a result, the surface becomes flat. Further, since the terrace is the (001) plane, the growth rate Vt has a value that cannot be ignored. For this reason, the quantum wire structure is only formed in the process of growth,
It was impossible to arrange the quantum wires in high density.
On the other hand, the present invention is characterized in that quantum wires can be continuously arranged because the steps do not disappear and grow laterally.

[0062]

EXAMPLE 1 As Example 1 of the present invention in FIG. 15, a GaAs / AlGaAs DFB having a primary diffraction grating with a pitch of 125 nm.
The laminated structure of the laser wafer is shown. Si-doped GaA
The s substrate 11 is 5 in the (100) plane direction from the (111) A plane.
This is a so-called tilted substrate in which the inclined surface is the substrate surface.
On top of this, the buffer layer 12 of Si-doped GaAs is 0.5
μm formed, and Si-doped Al _0.5 Ga _0.5 A
The s clad layer 15-13 is formed with a thickness of 1.5 μm.

Next, 15-14 is an optical confinement region of 200 nm.
Area Si-doped Al_y Ga_1-yAs, and this A
The content y of 1 gradually changes from 0.5, and the active layer 15-1
Near 5 it drops to 0.3. Active layer, multiple quantum well
Door is undoped Al_0.3 Ga _0.7 As10nm barrier
Layer and undoped GaAs 6nm well layer repetition?
It consists of 5 quantum wells. On top of this
Be-doped Al that is the optical guide layer 15-16_0.3 Ga_0.7 
An As layer having a thickness of 0.3 μm is formed. Laser interference dew on this surface
A resist pattern with a pitch of 250 nm is formed using the optical method.
Formed and dry-etched by secondary diffraction grating 15-1
Form 7. At this time, the groove direction of the lattice is (110)
Direction, that is, the normal of the original substrate and the (111) A plane
Normal to the plane defined by the normal.

After removing the resist residue and the oxide on the surface in the MBE chamber, an Al _0.3 Ga _0.7 As layer 15-18 having the same composition as that of the upper optical guide layer was formed thereon by an MBE method with an average film thickness of 0. 2 μm is grown to form a periodic step on the surface. The step is composed of a terrace surface composed of a (111) A surface having a width of about 225 nm and a step surface composed of a (001) surface having a width of about 38 nm. The cycle of repetition coincides with the cycle of the diffraction grating of 250 nm, and the height difference of the step is about 20 nm.

V is the growth rate of GaAs on a flat substrate.
00, Al _0.3 Ga _0.7 As growth rate is V03,
The progress velocity of the growth surface on the diffraction grating is Vg00, Al _0.3 Ga _0.7 As is Vg03 for GaAs, and the angle formed by the growth direction and the substrate normal is θg00, Al _0.3 Ga _0.7 As for GaAs (FIG. 16). (See (a) and (b)). In this embodiment, V00 = 11 nm / min, V03 = 15.
7 nm / min, θg00 = θg03 = 70.5
°.

Vg00 = V00 / cos θg00, Vg
Since 03 = V03 / cos θg03, the propagation velocity of the growth surface in the plane horizontal to the substrate surface is V100 = V00 / t.
anθg00, V103 = V03 / tanθg03. Thus, the horizontal propagation velocity of the growth surface becomes clear. In this embodiment, V100 = 29.5 nm / m
in, V103 = 42.1 nm / min.

By using this, by opening and closing the shutter, B
e-doped GaAs and Be-doped Al _0.3 Ga _0.7 A
The periodic structure 15-19 composed of the s layer is formed. That is,
The GaAs layer is grown for 1 minute and 41 seconds, and then AlGa
The As layer is grown for 1 minute 47 seconds, the GaAs layer is further grown for 1 minute 41 seconds, and then the AlGaAs layer is grown for 1 minute 47 seconds.
By the second growth, the periodic structure on the growth surface advances horizontally by 250 nm. In the meantime, about 88
nm growth surface is progressing. Further, at this time, the repeating period of the periodic structure in the direction horizontal to the substrate surface is 125 nm, and the refractive index modulation structure having a period of 1/2 of the pitch of the formed diffraction grating can be manufactured. The growth conditions were changed so that the growth rate on the (111) plane was also increased, and a Be-doped Al _0.3 Ga _0.7 As layer 15-191 was formed to a thickness of 0.2 μm to flatten the growth surface. _0.5 Ga _0.5 As Upper clad layer 1.5 μm 15
-192 and Be-doped GaAs cap layer 15-193
Of 0.3 μm to form an LD structure. The optical waveguide thus constructed has a thickness of 125 nm in the upper guide layer.
The equivalent refractive index is modulated by the thick portion of GaAs arranged for each.

Example 2 FIG. 17 shows, as Example 2 of the present invention, a waveguide with a diffraction grating having a periodic structure with a deformed shape. Si-doped Ga
The As substrate 17-71 is an inclined substrate having a surface inclined by 5 degrees from the (111) A plane in the (100) plane direction. On top of this, Si-doped Al _0.5 Ga _0.5 As clad layer 17-
72 is formed with a thickness of 1.0 μm.

Next, 17-73 is undoped Al _0.1 Ga
This is a waveguide layer made of _0.9 As200 nm. On top of this, a Be-doped Al _0.3 Ga _0.7 As upper optical guide layer is formed.
A layer 17-74 is formed to a thickness of 0.3 μm, a resist pattern having a pitch of 250 nm is formed on the surface by a laser interference exposure method, and a secondary diffraction grating is formed by dry etching. After removing the resist residue and the oxide on the surface in the MBE chamber, Al _0.3
After the Ga _0.7 As layer was grown and the step was formed on the surface, the material flow rate was controlled by the mass flow controller, and the Be-doped Al _0.1 Ga _0.9 As and Be were doped.
Periodic structure composed of doped Al _0.3 Ga _0.7 As layer 17-
Forming 75. Even when the growth surface cannot maintain the similar shape and a new facet surface appears, the modulation of the refractive index having the period of 1/2 of the pitch of the diffraction grating formed as shown in FIG. 9B. A structure can be produced.

By changing the growth conditions and increasing the growth rate on the (111) plane, Be-doped Al _0.3 Ga
_{A 0.7} As layer 17-76 is formed to a thickness of 0.2 μm to flatten the growth surface, on which a Be-doped Al _0.5 Ga _0.5 As upper cladding layer 1.5 μm 17-77 and a Be-doped GaAs are deposited.
A cap layer of 0.3 μm is formed.

Example 3 FIG. 18 shows a two-dimensional quantum well manufactured by this method. Substrate 18-41 is a Si-doped GaAs substrate which is a substrate. This substrate has a structure inclined by 2 ° from the (111) plane in the (110) direction. 18-42 S on this
i-doped AlGaAs (As composition 0.5) 1.5 μm
Grow. In addition, 18-43 Si doped AlGaA
s (Al composition 0.1) is grown to 0.4 μm, and the growth is temporarily stopped. This is taken out from the growth apparatus and a diffraction grating is formed by interference exposure.

The growth film having the diffraction grating thus formed is again placed in the growth chamber. This is shown in FIG.
It becomes a diffraction grating like 18-44. First, in order to have a buffer effect, Si-doped AlGaAs (A
l composition 0.3) is formed to 50 nm. As a result,
As described in 3 and 14, (111) plane and (10
The steps of the (0) plane are formed, and the width of the inclined plane (100) plane becomes about 10 nm. On the other hand, on the 18-45, and-type GaAs to be an active layer is grown to a thickness of about 10 nm on the (100) plane. At this time, the film thickness of GaAs is 3 on the (111) plane.
nm or less. 18-46 as a barrier over wells
-47 AlGaAs (Al composition 0.3) is formed to a thickness of 10 nm. Furthermore, 18-48 GaAs, which becomes a well, is
0) Form 100 above. The above is the active layer. On this, 18-49 optical guide layer Be-doped AlGaAs (Al
Composition 0.3) is formed to 100 nm. Further, Be-doped AlGaAs (Al composition: 0.
5) was grown to 1.5 μm. Finally, a Be-doped GaAs to be a cap layer is grown to a thickness of 0.5 μm to produce a laser. The threshold current density of the fabricated two-dimensional quantum well was improved by about 30% as compared with the ordinary one-dimensional quantum well.

Fourth Embodiment FIG. 19 shows a fourth embodiment of the present invention. The feature of this embodiment is that the carrier block layers 19-65 are provided. On the figure
Reference numeral 19-61 is a Si-doped GaAs substrate. This substrate has a (111) plane and is inclined 5 ° in the (110) direction. 19-62 Si doped AlGaA on this substrate
s (Al composition 50%) is grown to 1.5 μm. Furthermore,
An optical guide layer Si-doped AlGaAs of 19-63 (Al composition 10%) is grown to 200 nm, and the growth is temporarily stopped here. Here, a diffraction grating having a grating interval of 250 nm was formed by the interference exposure method as shown in Example 3. This is put in the growth apparatus again and regrowth is performed. Reference numeral 19-64 is an optical guide layer, which is made of Si-doped AlGaAs (Al composition: 0.
1) was formed to 100 nm on the (100) plane. Further thereon, 19-65 carrier block layer Si-doped Al
GaAs (composition 0.3) is formed to a thickness of 50 nm, and then an active region is laminated thereon. 19-66 is a barrier and-type AlGaAs (Al composition 0.3) (10
0) surface is grown to a thickness of 10 nm and subsequently formed as a well 19
A -67 undapped AlGaAs (Al composition: 0.1) is laminated so as to have a thickness of 60 nm on the (100) plane.
This repetition is repeated 19-68 (barrier), 19-69 (well), 19-70 (barrier), 19-71 (well). Furthermore, 19-72 is also a barrier, but it should be a little thicker,
Moreover, the selection ratio between the (111) plane and the (100) plane is reduced. The method is to lower the substrate temperature. The structure is 50 nm of AND-type AlGaAs (Al composition 0.3). Thereafter, a light guide layer 19-73 is laminated to a thickness of 100 nm. The structure is Be-doped AlGaAs, and the Al composition is increased from 0.3 to 0.5. 19-7 on it
Be doped AlGaAs, which is the clad shown in FIG. 4, is laminated in a thickness of 1.5 μm. Finally Be-doped AlGaA
By stacking 0.5 μm of s, a laser structure is formed. In this example, MOCVD was used for both primary growth and regrowth. In the case of gas-based growth, the selection ratio on the (111) plane and the (100) plane can be selected to be larger than that of solid source growth such as the MBE method, and a more stable quantum wire can be formed.

Example 5 FIG. 20 is a view in which a quantum wire manufactured by this method is used for a field effect transistor. A reference numeral 20-81 is an undoped GaAs substrate which is a substrate. It is the figure which turned the (110) plane substrate from 5 ° in the {111} direction. Reference numeral 20-82 is a layer in which a diffraction grating was formed and regrown to produce a quantum wire. The facets on which the quantum wires are formed are (110)
And (100) plane. Gas growth method MO
When the CVD method is used, this selection ratio can be selected to be 1:10 or more. 20-83 are contact layers corresponding to the source, drain and gate. 20-86, 20-8
Reference numerals 7 and 20-88 are electrodes.

Embodiment 6 FIG. 21 shows Embodiment 6 of the present invention. The diffraction grating 21-1 is formed on the surface of the GaAs substrate 1 inclined by 5 degrees about the [110] direction from the (111) plane by using the laser interference exposure method.
Was formed. The stripe direction of this diffraction grating is [11
0], and the period of this diffraction grating was 0.24 μm and the amplitude was 0.1 μm. A GaAs crystal and an AlGaAs crystal were grown on this diffraction grating by the GSMBE method using trimethylgallium (TMGa), triethylaluminum (TEAl) and AsH ₃ as source gases. The arrow 21-3 indicates the incident direction of the TMGa molecular beam and the TEAl molecular beam, which is inclined by 50 degrees from the normal direction of the substrate. An arrow 21-4 indicates the incident direction of the AsH ₃ molecular beam, which is tilted by 10 degrees from the normal line direction of the substrate to the side opposite to the TMGa molecular beam. These incident directions were kept constant without changing during the whole growth process.

21-5 is AlG grown on the diffraction grating
It is an aAs layer, on the surface of which there is a terrace 21-6 and a step 21-
A saw blade shape of 7 was formed. Here, the plane orientation of the terrace is (111), and the height of the step is about 2
It was 1 nm. At this time, the growth rate Vt in the direction perpendicular to the terrace surface was almost negligibly small, and a steady state in which the growth proceeded was achieved by the lateral movement of the step.

Next, the GaAs layer 21-having a thickness of 20 nm is formed in the lateral direction.
8 and 75 nm AlGaAs layers 21-9 were alternately grown, and further AlGaAs layers 21-10 and GaAs cap layers 21-11 were grown. As a result, AlGaAs
A two-dimensional superlattice 21-12, in which well regions of GaAs having a cross section of 21 nm × 20 nm are arranged in the barrier, was formed.

Embodiment 7 FIG. 22 shows Embodiment 7 of the present invention. Diffraction gratings 22-14 were formed on the surface of the GaAs substrate 13 tilted 5 degrees from the (111) plane with the [110] direction as the axis of rotation, using the optical interference exposure method. The stripe direction of this diffraction grating is [110]
Therefore, the period of this diffraction grating was 0.1 μm and the amplitude was 0.05 μm. On the diffraction grating, the solid raw material G
GaAs crystals and AlGaAs crystals were grown by MBE using a, Al and As. Arrows 22-15 represent the incident directions of Ga and Al molecular beams, and are inclined by 50 degrees from the normal line direction of the substrate. Similarly, arrow 22-16 is A
It represents the incident direction of the s molecular beam, and is inclined by 20 degrees from the normal direction of the substrate to the side opposite to the Ga molecular beam. These incident directions were kept constant without changing during the whole growth process.

22-17 is AlGa grown on the diffraction grating
It is an As layer, on the surface of which a terrace 22-18 and a step 22-
A saw blade shape consisting of 19 was formed. The plane orientation of the terrace was (111) and the height of the step was 21 nm. At this time, the growth rate Vt in the direction vertical to the terrace surface was about 1/10 of the lateral growth rate Vs of the step, and the steady state in which the growth progressed was achieved by the step moving substantially in the lateral direction. Next, 10 nm GaAs layer in the lateral direction
The AlGaAs layers 22-21 of 22-20 and 37 nm are alternately grown, and the AlGaAs layers 22-22 and GaA are further grown.
The s cap layer 23 was grown. As a result, AlGaAs
A two-dimensional superlattice 12 in which GaAs well regions each having a cross section of 10 nm × 21 nm are arranged in the barrier of FIG.

[0080]

By using an inclined substrate, it is possible to introduce a periodic structure having a period of 1 / N with respect to the periodic structure formed on the inclined substrate. Since the period of the diffraction grating is an integer fraction of the period of the diffraction grating formed by the interference exposure method, the period of the diffraction grating to be manufactured can be easily controlled by the interference exposure method. Furthermore, quantum wires can be obtained with good reproducibility.

According to the present invention, a quantum wire having a sufficient confinement effect on carriers in a semiconductor and a two-dimensional superlattice in which the quantum wires are arranged at a high density can be produced relatively easily and with good reproducibility. It became possible.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a step of a method for producing a diffraction grating by a conventional holographic interferometry method.

FIG. 2 is a cross-sectional view illustrating a step of a second conventional method.

FIG. 3 is a cross-sectional view illustrating a step of a third conventional method.

FIG. 4 is a conceptual diagram of one-dimensional, two-dimensional, and three-dimensional well structures.

5 is a diagram showing a relationship between electron state density and energy in the well structure shown in FIG.

FIG. 6 is a conceptual diagram showing growth of crystal planes.

FIG. 7 is a quantum thin line conceptual diagram in which a certain molecular species grows vertically in a crystal.

FIG. 8 is a diagram showing a sawtooth shape formed.

FIG. 9 is a diagram showing a formed new periodic structure (a) and modulation of an equivalent refractive index (b).

FIG. 10: 0.5-15 on a semiconductor substrate having a plane orientation of {111}
The schematic diagram which formed the long period structure which has a plane direction inclined by a degree.

FIG. 11 is a schematic view of manufacturing a short-period structure on the long-period structure of FIG.

FIG. 12 is an enlarged schematic view of a part of FIG. 11.

FIG. 13 is an enlarged schematic view of a part of FIG.

FIG. 14 is a schematic view of a laminated structure of steps having different growth directions.

FIG. 15 is a process chart showing Example 1 of the present invention.

FIG. 16 is a diagram showing a growth rate viewed from each direction.

FIG. 17 is a sectional view of a waveguide with a diffraction grating according to a second embodiment of the present invention.

FIG. 18 is a schematic view showing a two-dimensional quantum well laser manufactured according to Example 3.

FIG. 19 is a schematic view showing a two-dimensional quantum well laser manufactured according to Example 4.

FIG. 20 is a diagram in which the quantum wire produced in Example 5 is applied to a field effect transistor.

FIG. 21 is a diagram in which a grating 2 is formed on the surface of a GaAs substrate 1 tilted by 5 degrees about the [110] direction from the (111) plane by using a laser interference exposure method.

FIG. 22 is a diagram in which a grating 14 is formed on a surface of a GaAs substrate 13 tilted by 5 degrees about a [110] direction from a (111) plane by using a laser interference exposure method.

[Explanation of symbols]

1-21 Substrate 1-22 Photoresist 1-23 Laser beam 1-24 Laser beam 1-25 Photoresist mask 1-26 Periodic structure 2-27 GaAs substrate 2-27a Groove 2-28 Photoresist 3-29 Photoresist 3 -30 Substrate 3-31 SiNx Film 3-32 SiNx Film Etching Mask 3-33 Diffraction Grating 10-1 Sloping Surface 10-3 Flat Part 10-5 Slow Pitch of Substrate Surface 10-6 Periodic Structure 11-1 Inclination Surface 11-3 Flat part 11-5 Moderate pitch of substrate surface 11-6 Form in which short period structure overlaps long period structure 11-7 Short period structure 12-7 Short period structure 12-8 Semiconductor film 12-9 Semiconductor film 12-10 Semiconductor film 12-11 Saw-shaped 13-21 diffraction grating 13-22 Epitaxy consisting of stepped portion Law by membrane 14-31 quantum well 14-32 GaAs inclined substrate 15-13 SQW active layer of the laminate 14-33 stacked 15-11 Si-doped 15-14 Si-doped Al _y Ga _1-y As 15-15 active layer 15 16 Optical guide layer 15-17 Diffraction grating 15-18 Al _0.3 Ga _0.7 As 15-19 Be-doped Al _0.3 Ga _0.7 As 17-71 GaAs inclined substrate 17-72 Si-doped Al _0.5 Ga _0.5 As 17-73 Undoped Al _0.1 Ga _0.9 As 17-74 Be-doped Al _0.3 Ga _0.7 As 17-75 Second-order diffraction grating 17-76 Periodic structure 18-41 Substrate 18-42 Si-doped AlGaAs (Al composition 0.
5) 18-43 Si-doped AlGaAs (Al composition: 0.
1) 18-44 Diffraction grating 18-45 Well 18-46 Well 18-47 AlGaAs (Al composition 0.3) 18-49 Optical guide layer 19-61 Si-doped GaAs 19-62 Si-doped AlGaAs (Al composition 0.
5) 19-63 Si-doped AlGaAs (Al composition: 0.
1) 19-64 Optical guide layer 19-65 Carrier block 19-66 Barrier, undoped AlGaAs (Al
Composition 0.3) 19-67 Undoped AlGaAs (Al composition 0.
1) 19-68 Barrier 19-69 Well 19-70 Barrier 19-71 Well 19-72 Barrier 19-73 Optical guide layer 19-74 Clad, Be-doped AlGaAs 20-81 Substrate, Undoped GaAs 20-82 Diffraction grating 20- 83 Source, Drain, Gate 20-86 Electrode 20-87 Quantum Wire 20-88 Electrode 20-89 Electrode 21-1 GaAs Substrate 21-2 Grating 21-3 Incident Direction of TMGa Molecular Beam and TEAl Molecular Beam 21-4 AsH3 Molecule Line incident direction 21-5 AlGaAs layer 21-6 Terrace 21-7 Step 21-8 GaAs well region 21-9 AlGaAs barrier region 21-10 AlGaAs barrier layer 21-11 GaAs cap layer 21-12 Two-dimensional superlattice layer 22 -13 GaAs substrate 22-1 4 Grating 22-15 Incident direction of TMGa molecular beam and TEAl molecular beam 22-16 Ascending direction of AsH3 molecular beam 22-17 AlGaAs layer 22-18 Terrace 22-19 Step 22-20 GaAs well region 22-21 AlGaAs barrier region 22 -22 AlGaAs barrier layer 22-23 GaAs cap layer 22-24 Two-dimensional superlattice layer 51 Semiconductor substrate 52 Diffraction grating 53 Sawtooth shape 55 Diffraction grating 56 Sawtooth shape 61 First periodic structure 62 First growth layer 63 Second Periodic structure 81 GaAs 82 Al _0.3 Ga _0.7 As

Claims (17)

[Claims] 1. A semiconductor device comprising at least one layer of a second periodic structure, which is out of phase with the first periodic structure, on a semiconductor substrate formed with the first periodic structure. 2. The semiconductor device according to claim 1, wherein the period of the second periodic structure coincides with the first period. 3. The semiconductor device according to claim 1, wherein the second periodic structure is formed of a multilayer film. 4. A semiconductor substrate having a zinc blende type crystal structure, wherein the substrate at least partially has a plane orientation inclined in a range of 0.5 to 15 ° from a {111} plane, and the substrate surface is used. Sawtooth-shaped first periodic structure composed of {111} faces formed on the surface and one or more faces with other indices is formed, and crystal growth with different growth rate on the periodic structure depending on the plane orientation. A semiconductor device in which a second new periodic structure along the substrate surface is used as a quantum wire in the active region by advancing the growth surface in a direction that does not match the normal line of the semiconductor substrate using the method. 5. A semiconductor substrate having a zinc blende type crystal structure, wherein the substrate at least partially has a plane orientation inclined in a range of 0.5 to 15 ° from a {110} plane, and the substrate surface is used. Sawtooth-shaped first periodic structure composed of {110} face formed on the surface and one or more faces with other indices is formed, and crystal growth with different growth rate depending on the plane orientation is formed on the periodic structure. A semiconductor device in which a second new periodic structure along the substrate surface is used as a quantum wire in the active region by advancing the growth surface in a direction that does not match the normal line of the semiconductor substrate using the method. 6. The method according to claim 4, wherein the semiconductor growth method is M
A semiconductor device formed by the BE method. 7. The method according to claim 5, wherein the semiconductor growth method is M
A semiconductor device formed by the BE method. 8. The semiconductor device according to claim 4, wherein a part or all of the growth method is formed by a gaseous source material. 9. The semiconductor device according to claim 5, wherein a part or all of the growth method is formed by a gaseous source material. 10. A semiconductor substrate having a zinc blende type crystal structure, wherein the substrate at least partially has a plane orientation inclined in a range of 0.5 to 15 ° from a {111} plane. Sawtooth-shaped first periodic structure composed of {111} faces formed on the surface and one or more faces with other indices is formed, and crystal growth with different growth rate on the periodic structure depending on the plane orientation. A method of forming a diffraction grating, characterized in that a second new periodic structure is formed along the substrate surface by advancing the growth surface in a direction that does not coincide with the normal line of the semiconductor substrate using the method. 11. A semiconductor substrate having a zinc blende type crystal structure, wherein the substrate at least partially has a plane orientation inclined in a range of 0.5 to 15 ° from a {110} plane. Sawtooth-shaped first periodic structure composed of {110} face formed on the surface and one or more faces with other indices is formed, and crystal growth with different growth rate depending on the plane orientation is formed on the periodic structure. A method of forming a diffraction grating, characterized in that a second new periodic structure is formed along the substrate surface by advancing the growth surface in a direction that does not coincide with the normal line of the semiconductor substrate using the method. 12. The method according to claim 10 or 11, wherein a material having the same refractive index as that of the first periodic structure and the layer grown thereon is used, and only the second periodic structure acts as a diffraction grating. A method for forming a diffraction grating, which is characterized by the above. 13. The method of forming a diffraction grating according to claim 12, wherein the diffraction grating has a period of an integer fraction of the second periodic structure. 14. The formation method according to claim 13, wherein the vapor phase crystal growth method is MBE method, CBE method, GSMBE method,
A method of forming a diffraction grating, which is a MONBE method. 15. The method for forming a diffraction grating according to claim 14, wherein the vapor phase crystal growth method is a MOCVD method. 16. A semiconductor substrate having a diamond-type or zinc blende-type crystal structure and having a plane orientation inclined by 0.5 to 15 degrees from the orientation of the {111} plane or the {110} plane. In the above, a diffraction grating is formed on the surface of the substrate, and a semiconductor crystal is grown on the diffraction grating by a molecular beam epitaxy (MBE) method using a solid material or a molecular beam epitaxy (GSMBE) method using a gas material,
A method for producing a semiconductor crystal, characterized in that the central direction of at least one kind of molecular beam is inclined within a range of 10 to 80 degrees from the normal direction of the semiconductor substrate. 17. A method for producing a semiconductor crystal, wherein an energy band modulation structure is formed in an in-plane direction by changing the type of incident molecular beam during the crystal growth.